Messages

Great cars Alan! I have fun driving them - although only a few short laps so far.

Blue

Freestyle

Adlib

Farm

Kong

[1-17-50.rpl]

(Still, the issue of replays playing differently across DOSBox-running computers does sound worth investigating. Do you have any example replays at hand?)

Attached are two of my replays with this problem from ZCT251. I tried to collect all available data - thanks to @dreadnaut and @alanrotoi for the support. All information is from 06/2022.

1-17-50.rpl      
dreadnaut:
<= 6000 cycles: completes
>= 7000 cycles: crashes in the cork r/l just before the finish line
alanrotoi:
completes
frieshansen:
completes

1-17-45.rpl      
dreadnaut:
<= 6000 cycles: completes
>= 7000 cycles: crashes into the tunnel just after the cork l/r
alanrotoi:
completes
frieshansen:   
completes

Systems

dreadnaut:
DOSBox staging 0.76.0, DOSBox staging 0.78.1 -> all on Linux (not 100% sure about the OS anymore)
with the attached config dosbox-0.76-stunts.conf

alanrotoi:
DOSBox 0.74-3 with cpu speed 20000 cycles

frieshansen:   
DOSBox 0.74-3, DOSBox staging 0.76.0, DOSBox staging 0.78.0 -> all on Windows 10
DOSBox staging 0.76.0 -> on Linux (in a VM on Windows)
all with config file from dreadnaut


I tried a lot of things back then to somehow recreate the problem on my system, but failed with everything. At this point I lost confidence in a reliable replay by DOSBox and thought that the final decision about a valid replay should be decided with the help of the most accurate possible instance of the game itself. I have no problem with DOSbox per se and it is certainly the easiest way for us to drive, but for validation in extreme cases, I think it is poorly suited.
But I'm probably going a bit overboard here. If even the gurus of stunts like Duplode hardly know this problem, it is probably very rare. I also can't say for sure if it's really DOSBox - it's just a guess for which I have no proof.

Parodius

I have pretty strong feeling that if it is a rounding error/overflow this is either 100 percent reproducible on all machines (it is some kind of forgotten register which is not re-set in assembly when you press play instead of fast-forwarding) or 100 percent different on different real-life machines (I can only assume different execution of operations in a given processor/overflowing of registers on different systems) thus there is no "ultimate true system" (even with PCem) so we would end up with one arbitrary chosen and in that case I would choose DOSBox packed in official .zip file not because of accuracy but because of accessibility - even checking if a replay is valid on my computer was PITA - handling it via some API would be ridiculous for me.

My problem with DOSBox is that it plays some replays differently on different computers despite having the same version and config. That's why it's out of the question for me for a predictable system.

Although I have already benefited from a loose interpretation, I still think that a valid replay should run completely from start to finish. But we need a well-defined way to determine that.

My solution would be a closed and clearly defined reference system on which the replays are played. Only if they run completely through there, the replay is valid. The reference system should reflect as well as possible an installation of stunts on a real computer of that time. Nobody knows on which system we will play in 20 years and therefore it is good to orientate on the original - that will always be the reference.

In my opinion DOSBox is out of the question, because it is not very close to the hardware. Better would be the very accurate emulator PCem (but only because it can hardly be realized with a real computer ). The perfect solution for me would be a virtual system, to which the replay is transferred via an API. It then outputs whether the replay is valid or not. Maybe even with a video. The whole thing could then also be used in a competition so you know short time after the upload for sure if the replay is valid.

I understand the point that it's difficult to spot mistakes while creating the replay. But just like, for example, sometimes a penalty-time isn't spotted until too late after a difficult passage, that's part of stunts for me, too.

Whatever we decide in the end, I think it is important that there is a clear procedure / rule with which everyone can live and which leaves no more room for maneuver, so that we don´t need this discussions about such replays anymore. As long as the system described above does not exist, I am for the current rule.

P.S. Unlike in my last post, here the first letter of each word doesn't spell anything.

 

Very nice site - I like especially how you put together all the informations about Stunts.

You've done a great job with these live race videos.  They're really nice to watch and give a good idea of how it all went down.

I fully agree with that 

Nice - I'm glad that it now has another use.

Sierra